getPeakThresh: Function to return a specified flood threshold using data...

In jlthomps/EflowStats: Returns HIT/HAT Hydrologic Indicator stats for a given set of data

Description

This function accepts obs_data and peak_data data frames that contain observed data and peak annual flow data for the desired NWIS site and a 'perc' percentile value. It returns a value 'thresh' calculated by: 1.67-year flood threshold (Olden and Poff, 2003)-For indices FH11, DH22, DH23, DH24, TA3, and TH3, compute the log10 of the peak annual flows. Compute the log10 of the daily flows for the peak annual flow days. Calculate the coefficients for a linear regression equation for logs of peak annual flow versus logs of average daily flow for peak days. Using the log peak flow for the 1.67-year recurrence interval (60th percentile) as input to the regression equation, predict the log10 of the average daily flow. The threshold is 10 to the log10 (average daily flow) power (cubic feet per second). for the 5-year recurrence interval (80th) percentile, used by indices TL3 and TL4, follow the same process, inputing a different 'perc' value.

Usage

  getPeakThresh(obs_data, peakValues, perc)

Arguments

obs_data	data frame containing processed NWIS daily flow data for the site
peakValues	data frame containing NWIS annual peak flow data for the site
perc	value containing the desired percentile to be calculated

Value

thresh numeric containing the 1.67-year flood threshold

Examples

qfiletempf<-sampleData
sites<-"02178400"
peakValues<-getPeakData(sites)
getPeakThresh(qfiletempf,peakValues,.6)

jlthomps/EflowStats documentation built on May 19, 2019, 12:48 p.m.